Underwater kelp forests contain flora that reach to different heights - just like forests on land. One key part of these kelp forests is the understory, which consists of algal species that cover the rocky reefs in a rich mosaic of greens, reds, and browns.

Mainland vs. island understory kelp density

Figure App.E.10.20.. A figure showing the area covered by brown algae at two sites on Santa Cruz Island from 2000 to 2015.

Figure App.E.10.20.. A figure showing the area covered by brown algae at two sites on Santa Cruz Island from 2000 to 2015.

Click for Details Brown algae percent cover from LTER subtidal surveys at Santa Cruz Island (two sites, dark blue) and the mainland (nine sites, light blue) are shown in the trendlines above. Brown algae has been in decline since 2010 and is near record lows in the Santa Barbara Channel both at the mainland and in the sanctuary. Data source: SBC LTER; Figure: R. Freedman/NOAA

Mainland vs. island foliose red algae density

Figure App.E.10.21.. A figure showing the area covered by foliose red algae on Santa Cruz Island (dark line) and from the mainland coast (light line) from 2000 to 2015.

Figure App.E.10.21.. A figure showing the area covered by foliose red algae on Santa Cruz Island (dark line) and from the mainland coast (light line) from 2000 to 2015.

Click for Details Foliose red algae percent cover from LTER subtidal surveys at Santa Cruz Island (two sites, dark blue) and the mainland (nine sites, light blue) are shown. Red algae cover has been slowly increasing from the start of the dataset, but has remained stable at about 30 percent cover at both Santa Cruz Island and the mainland since 2010. Data source: SBC LTER; Figure: R. Freedman/NOAA